Linear rolling bearings of transmitting torque are used in virtually all areas of mechanical engineering and motor vehicle technology. Parts which can be displaced longitudinally with respect to one another can be mounted with bearings of this type. In applications with shafts whose lengths can be adjusted telescopically, a bearing of this type has to additionally transmit the torques which are passed through the shaft. Shafts whose length can be adjusted telescopically are used, for example, as steering shafts of steering columns of modern motor vehicles, In steering columns of this type, the position of the steering wheel in the passenger compartment can be adapted to the individual size and posture of the operating person. In this way, the absolute spacing of the steering wheel with respect to the steering gear is changed. This change in spacing can be corrected by two shaft ends which are arranged inside one another so as to be displaceable telescopically.
For example, DE 199 33 875 A1 discloses a linear rolling bearing with two profile elements that can be displaced satisfactorily in the longitudinal direction with respect to one another. This is achieved by the rolling mounting, the rolling bodies circulating in endless circulatory channels. Torques of small magnitude can be transmitted between the two profile elements via the rolling bodies. However, if the prevailing torque exceeds a critical value, the two profile elements rotate at least by a small rotational angle with respect to one another under resilient work, wall sections of both profile elements coming into contact with one another. The magnitude of the torque which is still transmitted via the rolling bodies can be defined by the design of the compressing elements. Above a critical torque, at any rate, the transmission takes place via the abovementioned contacts of the wall sections of the two profile elements with one another. In this known linear rolling bearing, the rolling bodies circulate in first and in second circulatory channels. Both circulatory channels have a loadbearing channel which is parallel to the longitudinal axis, torques or radial loads below the critical torque being transmitted between the two profile elements via the rolling bodies which are arranged in the loadbearing channel. Furthermore, said circulatory channels have a return channel which is parallel to the longitudinal axis and in which the rolling bodies return without load. The return channel and the loadbearing channel are connected to one another in an endless manner via deflection channels, with the result that the rolling bodies can circulate endlessly. The rolling bodies which are arranged in the loadbearing channel of the first circulatory channel can transmit torques in one rotational direction. The rolling bodies which are arranged in the loadbearing channel of the second circulatory channel can transmit torques in the opposite direction between the two profile elements.
Although the contact of the wall sections of the two profile elements with one another ensures that the rolling bodies of the two circulatory channels are not exposed to any excessively high loadings as a result of overcritical torques, it is to be noted that a simultaneous relative displacement of the two profile elements with respect to one another in the longitudinal direction is possible above the critical torque only with friction work. This is because sliding friction is caused during the contact of the wall sections, a frictional force being a function of the prevailing torque.